Incident Description
Major damage occurred to the Oroville Dam Service Spillway during spillway operation on February 7, 2017. Additionally, due to high inflows and reduced service spillway capacity, the ungated emergency spillway saw overtopping flow beginning on February 11, 2017, for the first time. Excessive erosion of the bedrock downstream of the emergency spillway threatened the stability of the structure on February 12, 2017. The reservoir was immediately lowered using the service spillway to prevent potential erosion of the emergency spillway’s foundation.